1. Field of the Invention
The invention relates to a battery and a battery pack. More particularly, the invention relates to a battery and a battery pack that uses a bolt as an electrode terminal.
2. Description of Related Art
Japanese Patent Application Publication No. 2013-048047 (JP 2013-048047 A), for example, describes a battery in which an electrode terminal of a positive electrode and an electrode terminal of a negative electrode are provided on a top plate (top panel or case cover) of a case. A battery pack in which high voltage is able to be output is able to be obtained by arranging a plurality of flat batteries parallel to one another, and electrically connecting these batteries in series.
If electrode terminals of both electrodes are provided on the top plate of the case, these electrode terminals need to be insulated from the top plate. The electrode terminals are electrically connected to a power generating element inside the case, and thus must be insulated from the top plate. Meanwhile, bolts are used for a portion of the electrode terminals described in JP 2013-048047 A in order to fix a bus bar or the like in place. The battery described in JP 2013-048047 A has the structure described below. Each of the electrode terminals of the battery described in JP 2013-048047 A is formed by a terminal bolt and a connecting terminal plate. An insulating plate is arranged on the top plate of the case, and the terminal bolt is arranged on this insulating plate, in such a manner that a top surface of a bolt head faces the insulating plate. On the other hand, the connecting terminal plate that is electrically connected to the power generating element inside the case and insulated from the top plate fits loosely over the terminal bolt, with the bolt head of the terminal bolt sandwiched between the connecting terminal plate and the insulating plate. A rotation stopping wall that restricts rotation of the terminal bolt is provided surrounding the bolt head, on the insulating plate (JP 2013-048047 A; FIG. 2). When fastening a nut onto the terminal bolt, a corner of the bolt head abuts against the rotation stopping wall, such that rotation of the bolt is restricted. Meanwhile, when a bus bar or the like is secured to the terminal bolt with the nut, the bus bar and the connecting terminal plate (i.e., the electrode terminal) are close contact, and the two are electrically connected.